body {
  font-family: Helvetica,Tahoma;
}

*,
*:before,
*:after {
  box-sizing: border-box;
}

.scroll-counter {
  position: fixed;
  top: 0;
  right: 0;
  padding: 15px;
  color: white;
  background-color: rgba(0,0,0,0.4);
}

.aos-all {
  width: 1000px;
  max-width: 98%;
  margin: 50px auto;
}

.aos-item {
  display: inline-block;
  float: left;
  width: 100%;
  height: 300px;
  padding: 20px;
}

.aos-item::before {
  content: attr(data-id);
  position: relative;
  width: 100%;
  height: 100%;
  float: left;
  background: #1da4e2;
  line-height: 260px;
  text-align: center;
  color: #fff;
}

@media screen and (min-width: 420px) {
  .aos-item {
    width: 50%;
  }
}

@media screen and (min-width: 1024px) {
  .aos-item {
    width: 33%;
  }
}

.aos-anchors__lines {
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  border-top: 2px solid blue;
  border-bottom: 2px solid red;
}

.aos-anchors__lines::before {
  content: '';
  width: 100%;
  height: 2px;
  position: absolute;
  margin: auto;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  background: green;
}

.aos-anchors__sidebar {
  position: fixed;
  left: 0;
  top: 0;
}

.aos-anchors__sidebar > div {
  padding: 5px 10px;
  background: #f1f1f1;
}

.aos-anchors__content {
  width: 400px;
  margin: 50px auto;
}

.aos-anchors__content > div {
  position: relative;
  width: 100%;
  height: 300px;
  margin-bottom: 50px;
  background: #f1f1f1;
  line-height: 300px;
  text-align: center;
  color: #333;
}

.aos-anchors__content > div::before {
  content: '';
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
}

.aos-anchors__content > div::after {
  content: attr(data-anchor-id);
  position: relative;
  background-color: #f1f1f1;
}

.aos-anchors__content > div[data-placement$="-bottom"]::before {
  background-color: red;
}

.aos-anchors__content > div[data-placement$="-center"]::before {
  background-color: green;
}

.aos-anchors__content > div[data-placement$="-top"]::before {
  background-color: blue;
}

.aos-anchors__content > div[data-placement^="top-"]::before {
  top: 0;
}

.aos-anchors__content > div[data-placement^="center-"]::before {
  top: 0;
  bottom: 0;
  margin: auto;
}

.aos-anchors__content > div[data-placement^="bottom-"]::before {
  bottom: 0;
}
